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Dengue: a mosquito-borne disease

Dengue is a mosquito-borne viral infection causing a severe flu-like illness and, sometimes causing a potentially lethal complication called severe dengue. Approximately, half of the world’s population is at risk and it affects infants, young children and adults. The incidence of dengue has increased 30-fold over the last 50 years. Up to 50-100 million infections are now estimated to occur annually in over 100 endemic countries, putting almost half of the world’s population at risk. Bangladesh is one of the countries that are affected by dengue viruses.

The Aedes aegypti mosquito is the main vector that transmits the virus that causes dengue. The virus is passed to humans through the bites of an infective female Aedes mosquito, which mainly acquires the virus while feeding on the blood of an infected person. The full life cycle of dengue fever virus involves the role of mosquitoes as a transmitter (or vector) and humans as the main victim and source of infection.

Once humans are infected, humans become the main carriers and multipliers of the virus; serve as a source of the virus for uninfected mosquitoes. The virus circulates in the blood of an infected person for 2 to 7 days, at approximately the same time that the person develops a fever. Patients who are already infected with the dengue virus can transmit the infection via Aedes mosquitoes after the first symptoms appear which normally occur within 4 to 5 days to maximum 12 days.

The clinical features of dengue fever vary according to the age of the patient. Dengue fever normally causes high fever (40°C/ 104°F) and at least two of these following symptoms:

Severe headache

Pain behind the eyes

Nausea

Vomiting

Swollen glands

Muscle and joint pains

Rash

In human recovery from infection by one dengue viruses provides lifelong immunity against that particular viruses serotype. However, this immunity confers only partial and transient protection against subsequent infection by the other three serotypes of the viruses.

In the meantime, here are some practical tips to minimize the breeding of Aedes aegypti mosquitos within our community

Environmental management: Changing the environment by destroying, altering, removing or recycling non-essential containers to minimize and/or prevent mosquito from breeding. This can help to minimize the vector propagation and human contact with vector-pathogen.

Mosquito-proofing of water-storage containers: Water tank storage can serve as larval habitats. Yet, it can be designed to prevent mosquitos from laying its egg on the surface of water by having fitted tight lids. If rain-filled, tightly-fitted mesh screens allow the rainwater to be harvested while keeping mosquitoes out. Moreover, removable cover should be replaced regularly and well-maintained to prevent damage which then allows mosquitos to have access to the water-tank.

Solid waste management: In the context of dengue vector control, ‘solid-waste’ refers to non-biodegradable items of household or community. A proper storage, collection and disposal of waste are very substantial. Therefore, “reduce, reuse and recycle” principle must be highly applicable to reduce larval habitats.

Street cleansing: A regular street cleaning including removing discarded water-bearing container and cleaning drainage on is very significant act to prevent mosquito from breeding.

Personal’s prevention: (1) wearing a light-colored clothes; (2) installing mosquito net on doors and windows; (3) hanging the mosquito net over the sleeping area to prevent mosquitos from biting. It is worth noting that Aedes mosquitos tend to bite during the day

Keep patients infected with dengue under a bed net at all times to prevent Aedes mosquitoes spreading the viruses to healthy people.

Editor’s Note:

This guideline has been adopted from Dengue Guidelines for Diagnosis, Treatment, Prevention and Control by World Health Organization (2009 Edition)